Voyage of discovery: Why you should buy a houseboat

For Nick and Hannah Cash, the best address in London is not Mayfair, Park Lane or Belgravia, but the River Thames.

Over the past nine years, they've lived aboard the Katharine of London, a 90ft houseboat moored at South Dock Marina, near Surrey Quays. A year ago their crew swelled by one, with the arrival of their daughter Liliana.

"It's such a beautiful way to live," says Hannah, who works as a solicitor for legal firm Yachting Lawyers (www.yachtinglawyers.com). "We're in the middle of a capital city, yet we live around ducks and swans and belong to a friendly community of fellow boat-owners. We'd find it really hard now to live in a conventional apartment or house on land."

A growing number of people now think that way, as more of us look for a simpler, cheaper lifestyle, closer to nature. In fact, the Residential Boat Owners' Association estimates that there may be as many as 15,000 houseboats in the UK, with between 30,000 and 50,000 people living on board.

"Demand for houseboats has always outstripped supply," says Brian Duckett, of Boatshed London (www.boatshedlondon.com), who is selling the Cashes' boat for £350,000 (they have to move for work reasons). "However, with the recession, that demand has gone to another level. All of a sudden, people find the notion of living on a boat not just romantic, but fashionable.

"It taps into aspirational, post-credit crunch ideas of a simpler, less carbon-greedy lifestyle."

What's more, it doesn't even have to be uncomfortable.

"Far from living in a state of constant cold and damp, we have central heating, an Aga and a wood-burning stove," says Hannah. "And every time we feel like it, we just untie our moorings and head off up river in our own home. We can get as far as Windsor - it's wonderful.